package ACWing.WeeklyRace;
//4784. 构造序列

import java.util.ArrayList;
import java.util.Scanner;

/**
 * @author :chenjie
 * @date :Created 2022/12/17 20:13
 */
public class StructuralSequence {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int m=sc.nextInt();
        ArrayList<Integer>list=new ArrayList<>();
        if(m<n-1||m>2*(n+1)){
            System.out.println("-1");
            return;
        }
        while (true){
            if(n==0&&m==0){
                break;
            }
            if(n==m){
                list.add(10);
                n=n-1;
                m=m-1;
                continue;
            }
            if(n==0&&m==2){
                list.add(11);
                m=m-2;
                continue;
            }
            if(n==0&&m==1){
                list.add(1);
                m=m-1;
                continue;
            }

            if(m>n){
                list.add(110);
                n=n-1;
                m=m-2;
                continue;
            }
            if(n>m){
                list.add(101);
                n=n-2;
                m=m-1;
                if(n==1&&m==0){
                    list.add(0);
                }
            }
        }
        for (Integer integer : list) {
            System.out.print(integer);
        }
    }
}
